A Physics Party Trick that Sucks [Liquid]

Fire consumes oxygen. If we 'trap' the fire inside a confined space, it will consume the oxygen inside it. Something will "want" to replace the now-empty space, so if we put liquid underneath our glass, it will be sucked right up, almost like magic.

Impress your friends with this cool little trick, that lets you see for yourself the power of suction!

And remember: Vacuum sucks, but physics never does.

Music by hoodless (www.hoodlessrocks.com) and is used with permission.

For more information:
www.smarterthanthat.com

Category:

Science & Technology

Tags:

• DIY
• suction
• liquid
• fire
• glass
• physics
• oxygen
• party
• trick
• fun
• smarterthanthat
• smarter
• than
• that
• mooeypoo

[mouser58907]

Where does the oxygen go? Conservation of mass/energy means it should still be there in some form right? Does it turn into heat energy?

[smarterthanthat]

There are 2 things at work here:

1. Combustion of the candle transforms the Oxygen molecules to H2O and CO2, which means there is less gas in the glass, and less pressure.

2. The candle heats the air BEFORE the glass is sealed by the water. When the oxygen runs out (from the chem reaction) and the candle burns out, the air cools, contracts, and creates pressure inside the cup.

Which one of these is the stronger reaction, I am not sure. If anyone has any ideas on how to test, drop me a word!

[bfosque]

The reason the milk rises is because of the temperature changes, not oxygen. PV=nRT, thus when the temperature drops after the candle goes out, the pressure inside the glass falls, causing the greater pressure of the air outside the glass to push the liquid up. It has nothing to do with the loss of oxygen, because, as someone mentioned before, it is simply replaced by CO2.

[smarterthanthat]

bfosque, you're right, and the equasion, indeed, holds true. But what I am not too sure about (there are corrections to the vid in the site, btw) is whether the milk/water rise because of temperature *OR* because of the volume change. After the chem reaction of the fire, there might be less pressure in the cup because some of the CO2 is now condensed H2O (lowered moles in the volume of the glass). Which is it - temp or chem reaction? not sure :)

If you have ideas to check this, let me know!

[lovasip]

You claim that there is practically vacuum in the glass.

Since the majority of air is inert gas like nitrogen, and oxigen simply turns into carbon-dioxide it is certainly wrong.

Check my comment on shane's video for an other explanation!

[smarterthanthat]

You are correct, I was wrong. I have changed most of the post already, and working on finding out a bit more about this. It seems like it wasn't just the heat/cooling of the oxygen either.. something else is happening here, and I'm going to figure out what! :)

Thanks for the correction.

[orangeman10987]

you said any liquid, i tried it with gasoline and it didn't work out too well.. =(

[canadian678]

HOLY COW THATS AWESOME!!!!!!!!!!!

[Mriknowimfresh]

@smarterthanthat who caressssssssss

[mattymuck]

@smarterthanthat But if the temperature inside the glass increases, it doesn't matter if the pressure starts to drop after the candle burns out because it will still be of a higher pressure than the surrounding atmosphere. I think the rate of the liquid coming in is proportional to the rate of cooling. So that the heat opposes the vacuum effects of combustion and as it starts to cool, combustion effects win and a vacuum starts to form. Maybe thats what you were saying in your last post though.

[ELTURBOMAN]

what if you smoke crack????

[pink94angel]

is that a chic or a gay man?

[GUYANESEGT]

i tried this with pure ethanol.... didn't work either lol

[TheNoobCS]

fuck u waste my entire time u nerd

[MAnGaThaBOy]

@smarterthanthat i can use any liquid i want? how about gasoline? xD

[kingt34]

I loled so hard at "The oxygen DIES!" idk why i just found it soo funny because you were really scientific until that point xD

[kingt34]

ROFL